Tangrams and constraint-based geometry.(Calculator And Computer Technology User Service)

Legend has it that a servant of a Chinese Emperor was carrying a very expensive square ceramic tray and when he tripped and fell it was shattered into seven pieces (called tans). He was not able to arrange the pieces back into the proper shape but he did realise that there were many other shapes that could be built from the pieces

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Tangrams have sometimes been used as an extension activity intended only to keep faster students busy while others finished essential desk-work. Without adequate introduction, many find that tangrams are just an open-ended form of jigsaw puzzle. Happily teachers have discovered that games provide an effective introduction to a new topic. In the case of tangrams, students are likely to learn more from their construction than from playing with the finished product.

This article describes how students can construct tangrams within a constraint-based geometric (CBG) environment, thereby learning much more than might be gained using scissors and cardboard, while at the same time learning to use the CBG system. The examples used here were constructed using a ClassPad 300 but might just as easily be developed using the Windows-based software package Geometry Expressions.

A major hurdle is one of definition. We may not expect too much trouble with student recognition …